A fan (1) has a rotor (10) and a fan impeller (20). The rotor (10) has a connecting portion (11) and the fan impeller (20) has a fastening portion (21). The impeller is centered relative to the rotor (10) with the fastening portion (21) on the connecting portion (11) by at least one centering element (40). The impeller is fixed to the rotor (10) by at least one fastening element (30). The fastening element (30) is a screw with a screw head (31), a threaded portion (33), and a shaft arranged between the threaded portion (33) and the screw head (31). A spacer sleeve (34) is arranged around the shaft. A thread (12) corresponding to the fastening element (30) is, respectively, formed in the connecting portion (11).

A fan and a balance ring for the fan are provided. The fan includes a housing, a hub disposed in the housing, blades connected to the side surface of the hub, and a balance ring connected to the hub. The balance ring includes a ring chamber and a balance liquid filled in the ring chamber. The volume of the balance liquid is less than the volume of the ring chamber.

A ceiling fan assembly having a motor with a rotor with multiple blade mounts, multiple blades having a removable blade tip, a balancing weight mount carried by the multiple blades and covered by the removable tip, and where each of the multiple blades are pre-balanced and indexed to a corresponding one of the multiple blade mounts.

A rotor for use in a gas turbine engine includes a wheel and a plurality of blades. The wheel is arrange about an axis of the gas turbine engine for rotation. The plurality of blades are arranged around the wheel and extend radially outward from the wheel to interact with gases flowing through the engine. One or more of the plurlaty of blades is formed to include a hole that extends into an external surface of the blade and a plug located in the first hole. The blade and the plug are made of different materials or have different densities to vary the frequency response of the blade.

In a vacuum pump, a portion of a lower end portion of a rotating cylindrical body is cut in an axial direction thereof to form an imbalance correction portion (removal portion). Preferably, the removal portion is formed so as to minimize an axial width of the rotating cylindrical body and set a circumferential width of the rotating cylindrical body to a value of not less than a thickness (width in a radial direction) of the rotating cylindrical body. Additionally, a corner formed in the removal portion is formed to have a large. With this configuration, in the rotating cylindrical body, the removal portion is formed to have a shape in which a removal width (depth) in the axial direction of the rotating cylindrical body is small and a removal width in the circumferential direction thereof is large.

A fan (1) has a rotor (10) and a fan impeller (20). The rotor (10) has a connecting portion (11) and the fan impeller (20) has a fastening portion (21). The impeller is centered relative to the rotor (10) with the fastening portion (21) on the connecting portion (11) by at least one centering element (40). The impeller is fixed to the rotor (10) by at least one fastening element (30). The fastening element (30) is a screw with a screw head (31), a threaded portion (33), and a shaft arranged between the threaded portion (33) and the screw head (31). A spacer sleeve (34) is arranged around the shaft. A thread (12) corresponding to the fastening element (30) is, respectively, formed in the connecting portion (11).

A rotor for a fluid machine includes a wheel that is supported for rotation about an axis of rotation. The wheel includes a back wall with an outer rim edge. The rotor also includes a plurality of blades that are attached to the back wall and that are spaced apart about the axis of rotation. Moreover, the rotor includes an inter-blade area on the back wall between neighboring ones of the plurality of blades. Furthermore, the rotor includes a balancing feature that is included in the inter-blade area on the back wall. The balancing feature intersects and defines part of the outer rim edge.

A turbine rotor includes a rotor body and a balancing weight slot defined in an exterior circumference of the body. The balancing weight slot has a first axial width and a first radially outward facing surface at a first radial distance from a rotor axis. The rotor also includes a balancing weight entry port defined in a portion of the exterior circumference of the rotor body and aligned with the balancing weight slot. The balancing weight entry port has a second axial width greater than the first axial width and a second radially outward facing surface at a second radial distance from the axis of the rotor body that is smaller than the first radial distance. A method may include machining the entry port into the rotor with a tool. The method may be applied to a new rotor, or to remove cracks initiating from a previous entry port.

A rotor assembly comprises a rotor having annular flange including a plurality of protrusions axisymmetrically disposed about the annular flange, each protrusion having a mounting aperture for selectively receiving a balancing feature, and a plurality of slots axisymmetrically disposed about the circumference of the annular flange between adjacent protrusions. Each slot has a pair of converging flat portions extending axially inwardly from an adjacent protrusion end, an inner flat portion at an inner end of each slot, and a pair of curved portions respectively joining each converging flat portion to the inner flat portion in each slot. Each slot has a depth at least as great as an adjacent mounting aperture depth extending normally from the adjacent protrusion end to a far end of the corresponding mounting aperture.

A turbine rotor includes a rotor body and a balancing weight slot defined in an exterior circumference of the body. The balancing weight slot has a first axial width and a first radially outward facing surface at a first radial distance from a rotor axis. The rotor also includes a balancing weight entry port defined in a portion of the exterior circumference of the rotor body, aligned with the balancing weight slot. The balancing weight entry port has a second axial width greater than the first axial width and a second radially outward facing surface at a second radial distance from the axis of the rotor body smaller than the first radial distance. A method may include machining the entry port into the rotor with a tool. The method may be applied to a new rotor, or to remove cracks initiating from a previous entry port.